The ds18b20 can take power in two ways. The circuit that i made is using the parasite power.
This time i used clear nail pail paint over the copper trace.
printed circuit board is designed in KiCad open source EDA tool.
UPDATE : 14 September 2018
Using nail paint as a substitute for PCB lacquer is a cheap solution. It should be avoided when making a rugged PCB. If their is a lot a mechanical vibrations and stress, then the nail paint will chip away leading to oxidation.
In my previous attempt at designing this board here. It was good. But to make the pcb smaller. I redesigned the pcb, i shifted some component here and there.
This PCB contains a 3.3v level shifter at the receiver pin.
Here are the schematics and pcb layout.
Etching time : 1 hour and 20 minutes
That’s very long time but the solution is used up. as this is a small board i don’t want to dip the board in new solution. Also i let the PCB sit for a while , and by doing this the etching is uniform and the i also found out that the traces are much sharper than before. So it is a good idea to let it sit for around 30 minutes before you shake the container. As i am doing this manually, so that is why it is a slow process.
This development is very basic. It provides the GPIO in the form of header. As i will be using this board for rapid development and learning different coding practices.
I designed this board in KiCad – a open source l tool. From schematics and PCB layout is designed in this software suite.
Here are the schematics and PCB layout.
As i don’t have a laser printer i used the free hand sketching of traces. It is a very long and tedious process. After tracing with permanent marker and letting it dry it for few minutes. I etched this PCB in ferric chloride solution. I use very diluted solution, few grams of ferric chloride in around 200 ml water.
Total Etching time is around 40 minutes, After the board has been etched it needs to be cleaned thoroughly. I used utensil cleaning powder for that. And rinsed the board under water. And then let it air dry for few minutes.
The development is created. But there are few issues that came while testing the board. When i tested the board the chip does not responds. While checking for shorts or no connection on the PCB. I found that capacitor is not blocking the alternating signal. rather it is showing a short. So i had to change the 22pf capacitor with a new one and the board now works perfectly fine.
Esp8266 runs on 3.3V and most microcontrollers run on 5v . The voltage difference can cause problems in communication or in the worst case it can burnout the esp8266. So to address this probelm i created this simple interfacing pcb.
Scan the LDR reading with the help of atmega32 adc pins. Send the captured data to a computer using ftdi, bluetooth ,wifi or zigbee. Run any free math processing tool and make a image. Increasing the Number of ldr increases the resolution of the image.